| 摘要 |
An automatic needle-retracting syringe (2,80), intended for single use applications, includes a barrel (4), having a needle end (6), a plunger end (8) and a bore (10), and a plunger (12) at the plunger end. A needle gasket (16) is slidably mounted within the bore to define a near region (18) and a far region (20). A hollow needle (28) is mounted to the needle gasket. A path (26) through the needle gasket connects the near region to the needle. A coil spring (40,82) biases the needle gasket from an extended position to a retracted position, the needle fully housed within the barrel at the latter. The extended position is maintained by a retaining capsule (44) wedged between a narrowed bore portion (42) and the needle gasket. The retaining capsule is a gelatin which weakens upon contact with the liquid injectant so that after the liquid injectant contacts the retaining capsule for a period of time, the spring breaks the capsule causing the needle gasket to be moved back to the retracted position, thus retracting the needle back into the barrel. In addition, a supplemental flow path from the near region to the ambient environment can be created by dissolving a gelatin barrier to help prevent reuse of the syringe.
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